A Comparative Study of the Hexahedral Elements in LS-DYNA for Crashworthiness Simulation

The mesh behaviour and convergence rate of six hexahedral element formulations in LS-DYNA were investigated by means of crashworthiness simulation. The element formulations are: constant stress solid element (ELFORM 1), fully integrated S/R (Selective Reduced) solid element (ELFORM 2), fully integrated S/R solid element with reduced transverse shear locking (ELFORM -1 and ELFORM -2), 20-noded serendipity element (ELFORM 23), and 27-noded fully integrated S/R quadratic solid element (ELFORM 24). FE-simulations of the axial crushing of aluminium profiles were set up with these element formulations. The convergence rate of each element formulation was investigated by varying the mesh resolution. For validating the simulation results, four extruded profiles with rectangular hollow cross-sections were experimentally tested under quasi-static axial crushing load. On that basis, the performance of each element formulation was investigated in terms of their convergence rate, accuracy, and computational cost to elaborate an approach for future tasks. Finally, various aspects which should be considered while using these element formulations for this class of problem are discussed.